I think that was the plan from the beginning, but she's too much of an unlikeable and mercurial freakbomb. there have been multiple stories of "shakeups" on her staff seeming to point to her being atrocious to people who aren't sycophants.

I think they were imagining one term for Joe and that she could be groomed to step in, but that dream died hard and now the party is stuck in a corner, trying to keep Joe animated until they can find someone with better likeability numbers than "a fresh turd you just slipped on"